Embodiments herein are directed security access. Embodiments include an electronic lock that executes a time-based cryptographic algorithm to compute a time-based access code. The electronic lock compares the time-based access code with a received access code, and grants access to one or more lock features when the time-based access code matches the received access code. Embodiments also include providing an unlock code, including receiving a lock identifier and a user identifier. The lock identifier and the user identifier are sent to a remote computer system, and an access code for the lock is received from the remote computer system. Embodiments also include an electronic lock that receives and verifies an access code that includes a validity start time and a validity end time. When the current time is within the validity start time and the validity end time, the electronic lock grants access to one or more lock features.